The subject matter disclosed herein relates to piezoelectric composites and, in particular, to 1-3, 2-2 and 3-3 piezoelectric composites for use in moist environments.
Conventional ultrasonic transducers are constructed from one or more piezoelectric elements. One type of ultrasonic transducer element is a piezoelectric composite comprising piezoelectric ceramic material surrounded by a piezoelectrically passive polymer matrix. Ultrasonic transducers formed from these piezoelectric composites can experience an unusually short lifetime, when the ultrasonic transducers are used in moist or underwater environments. These ultrasonic transducers show a reduction in gain early in their operational life. The use of what most would consider a watertight case is not effective due to the construction of the ultrasonic probes. Probe construction often requires use of multiple types of materials with different thermal expansion coefficients, which can lead to the formation of interface dis-bonds during manufacturing and/or operation. In addition, the front surface of the probe is designed to maximize acoustic transmission and is often very thin which allows water to quickly diffuse to the piezoelectric material. It is therefore desirable to provide an improved piezoelectric composite that addresses at least some of these shortcomings.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.